JPH01220328A - Semiconductor electron emission element - Google Patents

Abstract

PURPOSE:To stabilize an electron emission by making the impurity density of the P type semiconductor to which a Schottky electrode is joined to be in the density range in which an avalanche breakdown is made to occur, and impressing reverse bias voltage to the Schottky electrode and the P type semiconductor. CONSTITUTION:A Schottky diode is formed with a Schottky electrode 5 joined to a P type semiconductor 1, and the joining part of the diode is reversely biased. This enables a vacuum level to a lower energy level than the conduction band of the P type semiconductor, and a large energy difference can be obtained. Moreover an avalanche amplification is made to occur in this condition. This enables a much electron to be produced, and the emission efficiency of the electron can be improved. The impurity density of a semiconductor used is made in the density range in which an avalanche breakdown occurs. And the material having a low work function is used to a Schottky electrode material.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a semiconductor electron-emitting device, and more particularly to a semiconductor electron-emitting device that causes avalanche amplification and emits hot electrons.

[Prior Art] Conventionally, among semiconductor electron-emitting devices, those using avalanche amplification have a p-type semiconductor layer and an n-type semiconductor layer, as described in U.S. Pat. No. 4,259,878 and U.S. Pat. No. 4,303,130. A reverse bias voltage is applied to both ends of this diode to cause avalanche amplification to make the electrons hot, and cesium etc. are deposited to lower the work function of the surface. Some devices are known that are configured so that electrons are emitted from the surface of the semiconductor layer.

[Problems to be Solved by the Invention] In the above-mentioned conventional example, cesium and a cesium-oxygen compound are formed on the surface of the electron-emitting region in order to lower the work function of the electron-emitting region. (1) Ultra-high vacuum (~lO""'t
arr or higher), it will not operate stably unless it is used at (
2) The lifespan changes depending on the degree of vacuum. (3) There were problems such as efficiency changing depending on the degree of vacuum. In addition, hot electrons generated at the p-n interface lose energy due to scattering when passing through the n-type semiconductor layer, so
The type semiconductor layer needs to be made extremely thin (200 Å or less). For this reason, there are many problems in the semiconductor manufacturing process to create an extremely thin n9 semiconductor layer with uniformity, high concentration, and low defects, and it has been difficult to stably manufacture devices.

[Means for solving the fi'f point] In the semiconductor electron-emitting device of the present invention, the impurity concentration of the p-type semiconductor to which the Schottky electrode is bonded is set in a concentration range that causes avalanche breakdown, and the Schottky electrode A reverse bias voltage is applied to and the p-type semiconductor to cause electrons to be emitted from the Schottky electrode.

[Function] The present invention connects a Schottky electrode to a P-type semiconductor to form a Schottky diode, sets the impurity concentration of the P-type semiconductor to a concentration range that causes avalanche breakdown, and reverse biases the Schottky diode. By applying a voltage and causing avalanche amplification, electrons are stably emitted from the surface of the Schottky electrode.

Note that if the Schottky electrode is made of a low work function material, the work function of the electron emitting surface will be lowered, making it possible to stably emit electrons.

Hereinafter, the operation of the semiconductor electron-emitting device of the present invention will be explained using an energy band diagram.

FIG. 4 is an energy band diagram of the semiconductor surface in the semiconductor electron-emitting device of the present invention.

Note that here, a case will be described in which a low work function material is used as a constituent material of the Schottky electrode.

As shown in FIG. 4, the nn of the junction between the p-type semiconductor (in the figure, p indicates the p-type semiconductor part) and the low work function material (in the figure, T indicates the low work function material part) is equal to nn. By applying a reverse bias, the vacuum level EVAC can be set to an energy level lower than the conduction band EC of the p55 semiconductor, and a large energy difference ΔE can be obtained. By performing seven-balance amplification in this state, it becomes possible to generate a large number of electrons, which are minority carriers in a p-type semiconductor, and the electron emission efficiency can be increased. Also, since the electric field in the depletion layer gives energy to the electrons,
When the electrons become hot, their kinetic energy becomes greater than the temperature of the lattice system, and the electrons, which have a potential greater than the work function of one surface, can escape from the surface without losing much energy due to scattering.

Semiconductor materials used in the semiconductor electron-emitting device of the present invention include Si, Ge, GaAs, GaP, and GaAI.
P, GaAsP.

GaAlAs, SiC, BP, etc. can be used, but any semiconductor material can be used as long as it can form a p-type semiconductor.The larger the band gear 2pE of a zero-indirect semiconductor, the better the electron emission efficiency. .

The impurity concentration of the semiconductor used is within the concentration range where avalanche breakdown occurs, and in this case, maximum efficiency in contributing to hot electrons can be obtained by using the impurity concentration at the limit where the tunnel effect dominates the breakdown characteristics. Therefore, doping must be done to a concentration below that at which tunnel breakdown occurs.

The Schottky electrode material used in the semiconductor electron-emitting device of the present invention must be a material that clearly exhibits Schottky characteristics for p-type semiconductors, and generally has a work function φ and n! Schottky barrier eightite φBm for two semiconductors
There is a linear relationship between CJze, 27
4p 7B(b) JOHNWILEL & 5ON
S), for Si, φBn = 0.235φIIIk-0
, 55, and similarly to other semiconductors, as the work function becomes smaller, φBn decreases. In addition, in general, there is one φB! between the shutter barrier φBF and φBn for p-type semiconductors. Becomes I. As calculated from the above formula.

pg! by using materials with a low work function! A good Schottky diode can be manufactured using one semiconductor. Such low work function materials include IA, 2A,
Group 3A and lanthanide metals, IA, 2A, 3A
Group and lanthanoid silicides, IA, 2A, 3A
These include group and lanthanide borides, IA, 2A, 3A groups and lanthanide carbides, and the work functions of these materials are 1.5 to 4V, making them all good Schottky electrodes for p-type semiconductors. Becomes a material.

By using the semiconductor material, semiconductor concentration, and Schottky electrode material described above, a good Schottky type semiconductor electron-emitting device can be manufactured.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

1(A) and 1(B) are schematic configuration diagrams of a first embodiment of a semiconductor electron-emitting device of the present invention, FIG. 1 (Todoroki) is a plan view, and FIG. 1(B) is an A- It is a sectional view of part A.

As shown in FIG. 1 (^) (B), a p-type semiconductor substrate 1 (
In this example, 3X1016 (cm) on 5t (100)
-3) with an impurity concentration of py! ! Semiconductor layer (hereinafter referred to as p
layer) is formed by epitaxial growth using the CVD method, the photoresist is opened at a predetermined position using a photolithography resist process, P ions are implanted, and this is annealed for 7 times to form an n-type semiconductor region 3. Similarly, the photoresist is opened at a predetermined position by a resist process, B ions are implanted, and the p-type semiconductor region 4 is formed by seven anneals.

Next, a low work function material I, which will become the Schottky electrode 5,
CGd (φWk=3.I V) was deposited by 100 people, and 3
Heat treatment was performed at 50°C for 10 minutes to obtain Gd5iz.

At this time, the barrier eight φHP is 0.7V, making it a good Schottky diode. Furthermore, 5iO2J! and polysilicon are deposited, an opening for electron emission is formed using photolithography, and 5iO2J! is formed on the Schottky electrode 5 by selective etching. 6, an extraction electrode 7 was formed. Reference numeral 8 denotes an electrode for ohmic contact, which is formed by vapor depositing pattern A on the other side of the p-type semiconductor substrate 1. 9 is a reverse bias voltage Vd between the Schottky electrode 5 and the electrode 8.
10 is a power source for applying a voltage Vg between the Schottky electrode 5 and the extraction electrode 7.

In the above configuration, by applying the reverse bias voltage Vd to the Schottky diode, 7 balancer amplification occurs at the interface between the p-type semiconductor cell 4 and the Schottky electrode 5,
The generated hot electrons pass through the extremely thin Schottky electrode 5 and leak into the vacuum region.
0 or more drawn out to the outside of the element by the electric field of the extraction electrode 7 As described above, according to this embodiment, since ΔE is increased by the reverse bias voltage, the low work function material is limited to Cs, Cg-0, etc. Therefore, it becomes possible to select materials from the wide range mentioned above, and more stable materials can be used. Furthermore, since the electron emitting surface is a Schottky electrode made of a low work function material, the process of forming the surface electrode is simplified, making it possible to manufacture a semiconductor electron emitting device with good reliability and stability.

FIG. 2 is a schematic diagram of a second embodiment of a semiconductor electron-emitting device according to the present invention.

The present embodiment is configured to prevent crosstalk between elements in the semiconductor electron-emitting device of the first embodiment described above.

In this example, A is set so that the electron emission efficiency is high.
0.5Ga0.5Ag (Eg is about 1.8) is used.

As shown in FIG. 2, a semi-insulating GaAg (100) substrate 12a is doped with Be at 1018 (cm-3) while a PG layer 13 of All O, 5GaO, 5Ag is formed.
was epitaxially grown and then Be 1016 (c
Layer ""3) All G, 5Ga0.5A while doping
Evitacally grow two layers 2 of s.

Next, in FIB (focused ion beam), p
◆Be is implanted into a deep layer at approximately 180 keV so that the impurity concentration of the layer 11 becomes 10" (c-3), and Be is implanted so that the impurity concentration of the p-layer 4 becomes 5×1017 (c-layer-3). Si is implanted into a relatively thin layer at approximately 40 keV, and Si is implanted at approximately 80 keV so that the impurity concentration of the n-layer 3 is 1018 (cm-3). Also, protons or boron ions are implanted at an accelerating voltage of 200 ksV or higher. By implanting, element isolation regions 12b were formed.

Next, 7 anneals were performed at 800℃ for 30 minutes in arsine + N2 + H2 air flow, and after appropriate masking,
BaBB (φWk=3.4 eV) was deposited by about 100 people and annealed at a temperature of 600° C. for 30 minutes to form a Schottky electrode 5. Extracting electrodes 7 are formed in the same manner as in the first embodiment shown in FIGS.
/3 was oxidized to form Bad (φl1k=1.11). At this time, the Paris 7 node φOp was 0.9 V, which showed good Schottky characteristics, and the semiconductor electron-emitting device was able to take a higher current density than Si. According to this example described above, For example, by insulating the elements, crosstalk between the elements can be reduced when a large number of semiconductor electron-emitting elements are fabricated on a substrate, and each element can be driven independently.

In addition, by using a wide-gap compound semiconductor as the semiconductor and boride on the surface, a Schottky electrode with extremely good adhesion, low work function, and large Schottky barrier is formed, increasing electron emission efficiency. I can do it.

3(A) and 3(B) are schematic configuration diagrams when a large number of semiconductor electron-emitting devices of the second embodiment are formed in a line, and FIG. 3(A) is a plan view, and FIG. 3(A) is a plan view. (B) is C-C
It is a sectional view of a1l.

Note that the sectional view of section B-8 in FIG. 3(A) is the same as the sectional view of the second embodiment shown in FIG. Further, since the configuration of the semiconductor electron-emitting device is the same as that of the second embodiment, detailed explanation will be omitted.

As shown in Section 3 (A) and (B), semi-insulating GaAs (
10G) PG layers 4a to 4h and Schottky electrodes 5a to 5h were formed on a substrate 12a by device-on implantation.

In the above configuration, the electron emitting portion has L-line shapes 4a to 4a.
As shown in 4h, a large number of semiconductor electron-emitting devices are formed, and as shown in 5a to 5h, each electron source can be independently controlled by applying a reverse bias to a large number of electrodes. is possible.

[Effects of the Invention] As described in detail above, according to the semiconductor electron-emitting device according to the present invention, a Schottky diode is formed by joining a Schottky electrode to a p-type semiconductor, and the junction of the diode is reverse biased. By doing so, the vacuum level E'1
It is possible to set lAC to a lower energy level than the conduction band EC of a p-type semiconductor, resulting in a larger energy difference ΔE than before.
can be easily obtained. By causing further avalanche amplification, p5! By generating a large number of electrons, which are minority carriers, in a semiconductor and increasing the emission current, and then heating the electrons by applying a high electric field to a thin depletion layer, it is possible to easily extract the electrons into a vacuum.

In addition, since materials with a larger work function than cesium etc. can be used as Schottky electrode materials, the selection range of surface materials is much wider than before, and stable materials can be used to achieve high electron emission efficiency. can be achieved.

In addition, since conventional semiconductor formation technology and thin film formation technology can be used in the production of semiconductor electron-emitting devices, there are advantages such as the ability to fabricate the device of the present invention at low cost and with high precision using established technology. do.

The semiconductor electron-emitting device of the present invention is suitably used in displays, EB drawing devices, vacuum tubes, and can also be applied to electron beam printers, memories, and the like.

[Brief explanation of the drawing]

FIG. 1(^)(B) is a schematic diagram of a first embodiment of a semiconductor electron-emitting device of the present invention. FIG. 2 is a schematic diagram of a second embodiment of a semiconductor electron-emitting device according to the present invention. FIGS. 3(A) and 3(B) are schematic configuration diagrams when a large number of semiconductor electron-emitting devices of the second embodiment are formed in a line. FIG. 4 is an energy band diagram of the semiconductor surface in the semiconductor electron-emitting device of the present invention. tap type semiconductor substrate, 2, 11, 13. : P type semiconductor layer, 3: n type semiconductor region, 4.4a to 4h: p type semiconductor region, 5.5a to 5h rainbow key electrode, 6: 5i02 layer, 7: extraction electrode. 8. Electrode for niohmic contact, 9.10: Power supply, 12a: GaAs substrate. 12b: Element isolation region. Agent Patent Attorney Seki Yamashita Figure 1 (B) Figure 2 Figure 4 Figure 3

Claims (3)

[Claims] (1) The impurity concentration of the p-type semiconductor to which the Schottky electrode is bonded is set to a concentration range that causes avalanche breakdown, and a reverse bias voltage is applied to the Schottky electrode and the p-type semiconductor to form the Schottky electrode. A semiconductor electron-emitting device that emits electrons from an electrode. (2) The semiconductor electron-emitting device according to claim 1, wherein the Schottky electrode is made of a low work function material. (3) The semiconductor electron-emitting device according to claim 1, wherein the p-type semiconductor impurity is implanted by maskless ion implantation.